1. Field of the Invention
The present invention relates to a picture information reproducing and processing apparatus for generating a picture signal from picture information recorded, as the subcode of a coded information signal such as a digital audio signal, on a recording medium such as a video disc, a digital audio disc, and so on.
2. Description of Background Information
In the case of recording media on which are recorded contents of a movie source (or film source, in other words) such as video discs, it is general that superimposing characters such as captions (translation of dialogues) is recorded as a part of information forming a picture. On the other hand, conventional apparatuses for reproducing and processing picture information recorded on such a recording medium are constructed to simply reproduce the superimposing characters such as captions as a part of picture information obtained from a recording medium. With the conventional apparatuses for reproducing and processing picture information, superimposing characters are displayed only in the lower end part or the right end part of a picture screen, and such a mode of display is sometimes annoying. Thus, there have been a problem that viewers tend to fix the eyes on the displayed characters, and it becomes difficult for the viewers to follow the movement of picture on the whole to be watched attentively.
On the other hand, a system is now proposed in which picture information is recorded and reproduced in the form of the subcode on and from a digital audio disc having a diameter of approximately 12 cm which is generally designated as compact disc (referred to as the CD hereinafter). The subcode is made up of eight subcode bits, and bit groups forming the subcode are divided into eight channels denoted respectively by letters P, Q, R, S, T, U, V, and W. In the system in which the picture information is recorded and reproduced in the form of subcode, data corresponding to picture information is configured such that a symbol is formed by 6 bits of channels R through W out of the 8 bits forming the subcode, and 98 symbols are treated as one block, as illustrated in FIG. 1. Two symbols in the 98 symbols are used as a sync signal, and 24 symbols obtained by dividing the remaining 96 symbols, by four are treated as a minimum unit of data, i.e. a "pack", which constitutes one instruction of picture processing.
More specifically, the first symbol (referred to as symbol 0 hereinafter) of the 24 symbols shows one of several modes. A symbol 1 following this symbol 0 forms "instruction" which indicates the sort of instruction. Symbols 2 and 3 following the symbol 1 constitute a parity Q which is an error correction code. Symbols 4 through 19 following the parity Q constitute a data field, and include information such as color information. Finally symbols 20 through 23 following the data field constitute a parity P which is an error correction code for protecting the information in the "pack".
On the other hand, there are four modes, i.e. "zero mode", "line-graphics mode", "TV-graphics mode", and "user's mode". The "zero mode" is provided for a case where no operation is required for pictures on the display screen, that is, the original image is to be maintained, and all data in the "pack" are 0 for this mode.
The "line-graphics mode" is provided for such a case that a liquid crystal display is provided on the front face of the player, to display notes such as an explanation of a music selection. As shown in FIG. 2, a picture area being long sideways is formed by pixels which are arranged in 288 columns and 24 rows. In other words, each row includes 288 pixels and each column includes 24 pixels. The term "pixel" stands for the minimum display element of a picture, and it is general that the picture processing is performed by using picture composing units designated as "fonts" each of which is made up of pixels divided into 6 columns and 12 rows.
The number of "fonts" which can be displayed in the "line-graphics mode" is 48 in the lateral direction, and 2 in the column direction, and this area is designated as "screen area". For providing the scroll function, a line of "fonts" is added to the upper and lower outer peripheries and the right and left peripheries of the Screen area, to form a picture area having 60 "fonts" in the direction of row, and 4 "fonts" in the direction of column. The subcode is formed so that the picture processing is performed by using a memory having addresses each corresponding to each pixel in this picture area. In addition, the area outside the "screen area" is designated as "border".
The "TV-graphics mode" is a mode for displaying images on the TV screen, and a picture is formed by pixels arranged in 192 rows and 288 columns as illustrated in FIG. 3. The number of "fonts" which can be displayed in the "TV-graphics mode" is 48 in the direction of row, and 16 in the direction of column. Also in this "TV-graphics mode", the subcode is formed so that the picture processing is performed by using a memory having addresses each of which corresponds to each pixel in a picture area having 50 "fonts" in the direction of row, and 18 "fonts" in the direction of column, made by adding a line of "fonts" to the upper and lower peripheries as well as the right and left outer peripheries of the "screen area".
As instructions for the picture processing, there are an instruction for painting out the whole picture area by one certain color, an instruction for drawing a picture in one "font" on the screen by using two different colors, an instruction for moving the whole picture upward or sideways, and so on.
Additionally, in the 8-bit groups forming the subcode, the Q bits forming the channel Q include time information corresponding to the track length to a certain position of each information data which is recorded from the beginning of the program area of CD, and form address time data which can be used as positional data representing the recording position. On the other hand, the P bits forming the channel P form data including information relating to a pause between two music selections.
This system for recording and reproducing picture information as the subcode is designed so that sixteen picture channels can be designated respectively at maximum. Specifically, a "write font foreground/background" instruction, used in the "TV-graphics mode" for example, has such a structure as illustrated in FIG. 4. This is an instruction for writing font data of the symbols 8 through 19 in positions having a row address defined by the symbol 6 and a column address defined by the symbol 7. For the pixels whose font data is "0", a color of a color number determined by the "color 0" is designated as a background color. For the pixels whose font data is "1", a color of a color number defined by "color 1" is designated as a foreground color. At the same time, sub-picture channels can be designated by using four bits of the channels R and S of the symbols 4 and 5. By this feature, as many as sixteen picture channels can be designated. Sixteen sorts of picture are previously recorded on a disc for example, and on the playing side, a desired picture channel can be selected at the time of playing by this scheme of designating the picture channel.
In addition, there are numbers from "0" to "15" as the color number. Different sixteen colors are respectively corresponding to these color numbers from "0" to "15", and the sixteen colors indicated by the color number "0" through "15" are set by a "load CLUT color 0 through color 15 (load color look-up table color 0 through color 15)" instruction in the "TV-graphics mode". The "load CLUT color 0 through color 15" instruction is an instruction having a structure illustrated in FIG. 5, and setting the contents of a color look-up table showing the color of pre-set color numbers or foreground/background color numbers it is necessary to designate sixteen colors in total. However, since four bits are used respectively for each of RGB to indicate a color, two symbols are required for setting one color. Therefore, eight colors are set by one "pack " at most. With this circumstances, this instruction is divided into two instructions respectively designating eight colors of the first half, and eight colors of the second half.
The instruction code for the colors of the first half, i.e. the color 0 through the color 7, is determined to be "30", and the instruction code for the colors of the second half, i.e. the color s through color 15 are determined to be "31". The mixing of colors for each of the color number is as follows. Red color is represented by four bits of the channels R through U of even symbols allotted to the color number Green color is represented by four bits, i.e. two bits of the channels V and W following the channels R through U of the even symbols, and two bits of the channels R and S of odd symbols. Blue color is represented by four bits of channels T through W following the channels R and S of the odd symbols. Therefore, 2.sup.4 (=16) sorts of gray scales are available for each color, and preparation of 16.sup.3 (=4096) colors is possible since three colors (RGB) are used. In addition, a gray scale "0000" corresponds to the darkest state, and a gray scale "1111" corresponds to the brightest state.
In order to make it possible to display the picture obtained from a recording medium by the recording and reproducing system using the subcode, and the picture by a video format signal recorded on the recording medium such as a video disc by using an FM modulation, in a picture screen, it is proposed separately by the applicants of the present application and others, to set a code to be inserted as the symbol 0 as shown in FIG. 6 in order to designate an additional mode, that is, "graphic mode with motion picture" in addition to the "zero mode" the "line-graphics mode", the "TV-graphics mode" and the "user's mode" which are also used in conventional methods.
The structure of picture in the "graphics mode with motion picture" is identical with that in the "TV-graphics mode", and an instruction designated as "load transparency control table" having such a structure as shown in FIG. 7 is provided. This "load transparency control table" instruction is an instruction for designating the mode for each pixel in picture area. Three modes ar designated by this instruction, and those are namely, "transparent mode", "mixing mode", and "non-transparent mode". In these three modes, different values are selected for the mixing ratio between a video format signal obtained by the subcode and a video format signal which is recorded by multiplexing together with the coded information signal including the subcode.
The bits in the channels R through W of each of the symbols 4 through 8 and the channels R and S of the symbol 9 constitute a series of codes TCB-0 through TCB 15 which respectively designate one of modes which will be described later for each of the group of pixels to which one of colors, which are registered as color number "0" through color number "15", is allotted. FIG. 8 shows a relationship between bit patterns of the codes TCB-0 through TCB-15 and the modes designating the mixing ratio, and the mixing ratio in each mode.
With the recording and reproducing system which has been explained above, the picture obtained by the subcode of the digital audio signal ca be superimposed as the superimposing caption on a picture by a video format signal which is recorded, after being processed by an FM modulation process, with the digital audio signal by using a frequency multiplex recording system.
If an apparatus having a structure for only processing the instructions of picture processing, as a picture information reproducing and processing apparatus for reproducing picture information from a recording medium on which the picture information is recorded by this recording and reproducing system, the characters of the superimposing caption will be displayed only in a mode determined at the time of recording, and the display can sometimes become annoying.
On the other hand, with respect to conventional apparatuses for reproducing and processing picture information recorded on a recording medium by using the system of recording picture information as the subcode, the structure is such that picture information of a designated channel out of picture information obtained from the recording medium is selectively taken-in and written in a single memory, and a picture signal is generated by repeatedly reading contents stored in that memory. However, in this system of recording and reproducing picture information as the subcode, the time period necessary for displaying a picture of one "font" is about 3.3/1000 second, and about 2.5 seconds are necessary for displaying 48.times.16 characters. Further more, picture information of all channels are not always recorded correspondingly to each music selection, and there may be a case that picture information of the same channel is recorded in positions which are separated from each other. Thus, in conventional picture information reproducing and processing apparatuses, stored contents of the memory are not immediately rewritten to data of a newly designated channel when the designation of channel has changed. Instead, the contents of the memory will be gradually rewritten to the data of the designated channel.
As a result, with the conventional picture information reproducing and processing apparatuses, there can be such a case that pictures of different channels are displayed at different positions of a picture screen. Therefore, if the superimposing captions of several different languages are recorded respectively in several channels and the apparatus is designed that the cap ion of a desired language is superimposed by designating one of the channels, then the language of the superimposed caption can be different between the first half and the second half of the superimposed caption when the designation of the channel is switched during the display operation.